For example, an image reading apparatus can read an image of an original document set on a document table. Further, the image reading apparatus includes an auto document feeder (ADF) and can read an image of an original document conveyed by the ADF. In this way, the image reading apparatus is adapted to two reading systems for reading the set original document and reading the conveyed original document.
In recent years, document conveying speed by an ADF is further increased. An image reading apparatus mounted with a high-speed adapted ADF can quickly read an image of an original document conveyed at high speed by the high-speed adapted ADF. The image reading apparatus mounted with the high-speed adapted ADF is configured to quickly read an image of a set original document. Specifically, in the image reading apparatus adapted to the high speed, two kinds of reading processing for the set original document and a conveyed original document are increased in speed. The speeds of the two kinds of reading processing having the same reading magnification are substantially the same.
On the other hand, there is a need for not only a relatively expensive image reading apparatus adapted to the high speed but also a relatively inexpensive image reading apparatus adapted to medium-low speed. In the image reading apparatus adapted to the medium-low speed, the two kinds of reading processing for the set original document and the conveyed original document are adapted to the medium-low speed. The speeds of the two kinds of reading processing are substantially the same.
This means that, in order to provide the image reading apparatus adapted to the high speed while providing the image reading apparatus adapted to the medium-low speed, a medium-low-speed reading unit for realizing medium-low speed reading processing for the set original document by the image reading apparatus adapted to the medium-low speed and a high-speed reading unit for realizing high-speed reading processing for the set original document by the image reading apparatus adapted to the high speed are separately manufactured and developed. Therefore, loads of the manufacturing, the development, and the like are heavy.